1. Field of the Invention
The present invention relates to a contact detection probe and, more particularly, to a touch probe used in a three-dimensional coordinate measuring unit.
2. Related Background Art
In a three-dimensional measuring unit or the like, a probe is brought into contact with an object to be measured placed on a table, and the contact point is three-dimensionally detected to perform stereoscopic measurement of the object having a complicated shape. In this measurement, an error in detection of the contact point results in an error in a measured shape.
A general mechanism of a conventional touch probe used in a measuring unit of this type is as follows. Three pins provided on a table for holding a feeler are supported by three V-shaped support portions, and the pins and the support portions serve as electric contacts to form a closed circuit. When the feeler is brought into contact with and urged against an object to be measured, the contacts are opened to obtain a touch signal.
In the conventional techniques as described above, since the three pins of the feeler are urged against the contacts by springs, the pins must be lifted against basing forces of the springs in order to open the contacts. Therefore, it is difficult to reduce a measuring force.
In addition, the measuring force has directivity because three contacts are present. Therefore, an uncorrectable error is caused in a measurement result.